Device, method, and aircraft for illuminating in-flight operations

ABSTRACT

An device, method, and aircraft are provided for illuminating an in-flight operation, the device, method, and aircraft generating an electromagnetic radiation within the far-violet and ultraviolet spectrum, and thus being imperceptible to the naked eye, compatible with night vision equipment, and undetectable by night vision equipment.

FIELD OF THE INVENTION

The invention relates generally to in-flight operations involvingaircraft and more particularly to providing a device, method, andaircraft for illuminating an in-flight operation, such as fuel transfer,that entails generating an electromagnetic radiation within thefar-violet and ultraviolet spectrum.

BACKGROUND OF THE INVENTION

An in-flight operation involves one or more aircraft performing amaneuver or exercise. One example of an in-flight operation is in-flightrefueling. In-flight refueling is a strategic method to extend the rangeand effectiveness of aircraft when it is not feasible or desirable toland for ground refueling. An in-flight refueling operation typicallyinvolves a supplying aircraft (e.g., a tanker) and a receiving aircraft(e.g., a fighter, bomber, transport, or command and control aircraft).The supplying aircraft holds a substantially steady flight positionwhile the receiving aircraft maneuvers into a refueling envelope behindand below the supplying aircraft. In one refueling method, the supplyingaircraft lowers a boom with an attached refueling nozzle that ismaneuvered by an operator to make contact with a refueling receptacle onthe receiving aircraft. In a second refueling method, the supplyingaircraft releases a refueling hose with an attached drogue within anappropriate range of the receiving aircraft. The receiving aircraft mustmaneuver so that a probe extending from the receiving aircraft makescontact with the drogue from the supplying aircraft. Present in-flightrefueling systems commonly use a camera vision system (e.g., a remoteaerial refueling operator (RARO) system as used on the Boeing KDC-10 andKC-767A/J) in which a video camera is pointed at the refueling envelopeand a refueling operator views a display to perform operations. Acomputer system is also commonly used to process and enhance the displayimages. Sufficient illumination is needed for the video camera so thatan operator viewing a display has good visibility of the refuelingoperation.

One challenge of in-flight refueling is providing sufficientillumination for the RARO system when performing night time in-flightrefueling. It is desirable to minimize the use of visible light (e.g.,radiation in the electromagnetic spectrum visible to the naked humaneye) during a night time in-flight refueling operation. One reason isbecause it is desired that an observer's attention not be drawn to therefueling operation. For example, an observer on the ground may perceivethe visible light on a supplying aircraft during night time at a fardistance when the atmosphere is substantially free of cloud cover, fog,dust, or other weather conditions which may obstruct visible light. Inanother situation, the observer may be in another aircraft instead of onthe ground. Thus, there is a need for an illumination system that isimperceptible to the naked eye such that an observer on the ground or inan aircraft would not perceive the illumination being used during thein-flight refueling operation at night time and under substantiallyclear weather conditions.

A second reason why it is desirable to minimize the use of visible lightis because the visible light interferes with night vision equipment(e.g., night vision goggles or night vision imaging systems). Duringnight time operations, pilots wear night vision goggles (NVG). Nightvision imaging systems (NVIS) may also be used onboard an aircraft.Visible light interferes with night vision equipment by causing“blooming”, loss of sensitivity, and is also destructive to the nightvision equipment by over saturating the sensors. Even if night visiongoggles are not used, the visible light can “blind” a pilot who looksdirectly into the light. Because the use of visible light is minimizedor eliminated in night time in-flight refueling, there may beinsufficient illumination such that the RARO cannot generate a practicalimage for use by the operator. Thus, there is a need for an illuminationsystem for in-flight refueling that provides sufficient illumination fora camera vision system such as a RARO, and is compatible with nightvision equipment.

Another challenge for night time in-flight refueling is to provideillumination that is uniformly incident on the receiving aircraft.Non-uniform illumination can cause glint, shadows, blooming, and glarewhen viewing the receiving aircraft through the camera and displaysystem. Non-uniform illumination also makes it more difficult forcomputer systems to enhance images. For example, image enhancementalgorithms that improve contrast may bring out detail in a darker partof an image, but may saturate and wash out the brighter parts of theimage causing other detail to be lost. Adding to the challenge is thefact that a receiving aircraft comes in different shapes and sizes. Whenin the refueling envelope, providing uniform illumination incident on afighter aircraft such as an F-16 may be substantially different thanproviding uniform illumination for a large command-and-control aircraftsuch as an E-3 AWACS. Furthermore, not all receiving aircraft have thesame location for their refueling receptacles. Some refuelingreceptacles may be on the centerline of the main fuselage, some are offthe centerline (e.g., F-15), and some may be in the nose (e.g., A-10Warthog). Thus, there is a need for a system that provides illuminationthat is also configurable to provide uniform lighting over the receivingaircraft and around the refueling receptacle for different types ofreceiving aircraft.

Although solutions have been offered for illuminating in-flightrefueling operations, many challenges still exist. As previouslymentioned, radiation in the electromagnetic spectrum visible to thehuman eye is detectable, causes blooming and may be destructive to nightvision equipment. Thus, visible light is not an effective solution.Illumination in the infrared (IR) or near-infrared electromagneticradiation spectrum has been proposed as a solution that is undetectableto the naked eye. However, it is possible that aircraft or groundforces, also equipped with night vision equipment, may detect theinfrared light making the supplying or receiving aircraft a vulnerabletarget, and thus, compromise the mission. In addition, because nightvision goggles are especially sensitive to IR or near-IR radiation,persons wearing night vision goggles may also be “blinded” by too muchillumination in the same manner when a person is blinded by headlightsof another vehicle.

Therefore, there exists a need for a system that provides illuminationthat is imperceptible to the naked eye and night vision equipment forin-flight operations such as in-flight refueling. The illumination ofthe system also needs to be compatible with night vision equipment, andthe system should be configurable to uniformly illuminate differenttypes of receiving aircraft for in-flight refueling.

SUMMARY OF THE INVENTION

A device, method, and aircraft for selectively illuminating an in-flightrefueling operation between a supplying aircraft and a receivingaircraft is provided. The invention is advantageously compatible andundetectable with night vision equipment, and imperceptible to the nakedhuman eye. The illuminating device comprises at least one emittingdevice that generates electromagnetic radiation at wavelengths withinthe far-violet and ultraviolet spectrum. A housing can be provided tohost the emitting devices and may be configured to direct the emittingdevices to illuminate the receiving aircraft.

In one embodiment, the emitting device generates an electromagneticradiation between about 370 nanometers (nm) to 420 nm. In otherembodiments, each one of the emitting devices may be configured as partof one or more emission banks, such that each emission bank may beindividually activated with a selecting device. The illuminating devicemay also comprise a control device to configure the intensity of theemitting devices.

In accordance with another aspect of the invention, a method fortransferring fuel comprises generating an electromagnetic radiation atwavelengths within the far-violet and ultraviolet spectrum, directingthe electromagnetic radiation to illuminate the receiving aircraft whenthe receiving aircraft is in an in-flight refueling envelope, and usingthe illumination to monitor and control the receiving aircraft positionwhen transferring the fuel from the supplying aircraft to the receivingaircraft. In other aspects of the invention, the method furthercomprises selecting an emission bank for generating the electromagneticradiation and configuring the intensity of the electromagneticradiation.

In accordance with another aspect of the invention, an aircraft equippedto illuminate an in-flight refueling operation between a supplyingaircraft and a receiving aircraft comprises an illuminating deviceattached to the supplying aircraft, a video camera aligned to view thereceiving aircraft, and a display device for displaying an image of thereceiving aircraft. The illuminating device is adapted to generateelectromagnetic radiation at wavelengths within the far-violet andultraviolet spectrum upon the receiving aircraft when the receivingaircraft is in an in-flight refueling envelope.

The device, method, and aircraft of the invention using anelectromagnetic radiation within a far-violet and ultraviolet spectrumis thus advantageous for illuminating an in-flight refueling operation.Furthermore, the inventive aspects of directing, selecting, andconfiguring the emitting devices advantageously accommodates differenttypes of receiving aircraft and in-flight operations to provide moreuniform illumination. Still other advantages of the invention will beapparent to those skilled in the art from the following detaileddisclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a supplying aircraft adapted for an in-flightrefueling operation between the supplying aircraft and a receivingaircraft in accordance with one embodiment of the invention.

FIG. 2 illustrates one embodiment of an illuminating device of theinvention.

FIG. 3 illustrates a block diagram of another embodiment of anilluminating device of the invention.

FIG. 4 illustrates a flowchart for a method for transferring fuel from asupplying aircraft to a receiving aircraft in an in-flight refuelingoperation.

DETAILED DESCRIPTION OF THE INVENTION

Embodiments of the invention are directed to a device, method, andaircraft for illuminating an in-flight operation. Specific details ofvarious embodiments of the invention are set forth in the followingdescription and in FIGS. 1-4 to provide a thorough understanding of theinvention. One skilled in the art will understand that the invention mayhave other embodiments and this description should not be construed aslimited to the embodiments set forth herein.

FIG. 1 illustrates a supplying aircraft 100 adapted to provideillumination for a typical in-flight refueling operation. The supplyingaircraft 100 holds a substantially steady flight position while areceiving aircraft 101 maneuvers into a refueling envelope 102. Therefueling envelope 102 is an acceptable volume of area, relative to thesupplying aircraft 100, in which receiving aircraft 101 must reside inso that a boom 103 can be extended from the supplying aircraft 100 tothe receiving aircraft 101 for the refueling operation. The refuelingenvelope 102 also sets forth the volume of area that must be adequatelyilluminated for the operation. An illuminating device 104 may beattached to the rear fuselage of the supplying aircraft 100 and adaptedto generate an electromagnetic radiation 105 at a wavelength within thefar-violet (about 400 nm to 420 nm) and ultraviolet spectrum (about 10nm to 400 nm). In other words, the illuminating device 104 generateselectromagnetic radiation between about 10 nm to about 420 nm. Theilluminating device 104 provides sufficient illumination for the volumein the refueling envelope 102. A video camera 106 adapted to senseelectromagnetic radiation in the far-violet and ultraviolet (UV)spectrum, may be aligned to view the in-flight operation. The videocamera 106 may be a conventional video camera which is generallysensitive to wavelengths between about 370 nm to 420 nm, or aspecialized UV camera. One example of a UV camera is a Sony XCD-SX910UVCCD camera which is sensitive to wavelengths between about 200 nm to 380nm. Images from the video camera 106 are provided on a display device107 located inside the supplying aircraft 100 to an operator tofacilitate positioning of the boom 103, monitoring the transfer of fuelfrom the supplying aircraft 100 to the receiving aircraft 101, anddisengaging the boom 103. In other embodiments, the supplying aircraft100 may be adapted to illuminate an in-flight refueling operation when adrogue and probe are used. For example, a supplying aircraft maygenerate an electromagnetic radiation between about 10 nm to 420 nm thatis directed to illuminate a hose, drogue, probe, and receiving aircraft.A video camera and display may be used to view and monitor the refuelingoperation as the supplying aircraft releases a refueling hose, thereceiving aircraft maneuvers into position to make contact between theprobe and the drogue, and the fuel is transferred from the supplyingaircraft to the receiving aircraft.

In one embodiment, the illuminating device 104 may be adapted such thatthe electromagnetic radiation 105 may be dispersed in arc between about30 degrees and 60 degrees to illuminate the receiving aircraft 101 inthe refueling envelope 102.

In another embodiment, the illuminating device 104 generateselectromagnetic radiation 105 in the range between about 370 nm to 420nm. This range is within the sensitivity of most conventional videocameras, and thus, existing camera vision systems for in-flightrefueling and commercially available video cameras may be used. Otherembodiments may further comprise a computer system to process andenhance the video images, such as the remote aerial refueling operator(RARO) system. It should be understood that embodiments of the inventionmay also be used for in-flight operations other than refueling. Foroperations such as in-flight aircraft inspection, maintenance, cargotransfer, re-armament, or other operations, further embodiments of theinvention may have the illuminating device 104 attached to differenttypes of aircraft and in different locations on an aircraft. Forexample, the illuminating device 104 may be attached to a transportaircraft and adapted to illuminate the cargo doors to allow cameravision monitoring of operations involving cargo or ordinance.

FIG. 2 illustrates one embodiment of the illuminating device 104. Theilluminating device 104 is comprised of a housing 201 and at least oneemitting device 202 for generating electromagnetic radiation within thefar-violet and ultraviolet spectrum. In one embodiment, the housing 201may be comprised of a first planar section 203 and a second planarsection 204. Each planar section has at least one emitting device 202which may be rectangular shaped and arranged in an array for simplicityof manufacturing and wiring. The first planar section 203 and the secondplanar section 204 are displaced from each other by an angle 205 ofbetween about 120 degrees and 150 degrees. In this embodiment, the firstplanar section 203 directs the electromagnetic radiation 206 towards thetop of the front fuselage section (e.g., canopy area) of a receivingaircraft 101, and the second planar section 204 directs theelectromagnetic radiation 207 towards the top of the fuselage midsection(e.g., between the canopy and tail) of the receiving aircraft 101. Inone embodiment, the second planar section 204 may house a greater numberof emitting devices 202 than the first planar section 203 to uniformlyilluminate the receiving aircraft 101 by accounting for the differencein distance between the illuminating device 104 and different sectionsof the receiving aircraft 101. In one embodiment, the housing 201 may bea rigid structure for simplicity, wherein the angle 205 between firstplanar section 203 and the second planar section 204 is fixed. In otherembodiments, the housing 201 may be hinged, gimbaled or otherwisemoveable such that the angle between the first planar section 203 andsecond planar section 204 may be changed. In yet further embodiments,the housing 201 may have more than two planar sections oriented atdifferent angles, have a curved surface, or be shaped as needed todirect the emitting devices 202 for the specific in-flight operation.

Each emitting device 202 is adapted to generate electromagneticradiation primarily within the far-violet and ultraviolet spectrum (forexample, between about 10 nm to 420 nm). In one embodiment, the emittingdevice 202 generates electromagnetic radiation between about 370 nm to420 nm. This range is within the sensitivity of most conventional videocameras and existing camera vision systems for in-flight refueling. Inanother embodiment, the emitting device 202 may be comprised of aplurality of ultraviolet light emitting diodes (LEDs). An example of anultraviolet LED is Nichia Corporation ultraviolet LED model NSHU590Awhich radiates electromagnetic radiation between about 360 nm and 400nm, with a peak at 375 nm. In one embodiment each ultraviolet LED may bearranged to be as close as possible to an adjacent ultraviolet LED asspace permits. This arrangement simplifies a wiring scheme for theplurality of ultraviolet LEDs. The arrangement of the plurality ofultraviolet LEDs of the emitting device 202 is not limited to anyparticular shape or spacing between ultraviolet LEDs. The emittingdevice 202 may be different sizes and different shapes to radiateelectromagnetic radiation as a floodlight, spotlight, signal light, ormarker light. In other embodiments, an emitting device 202 may becomprised of one or more ultraviolet lasers for generatingelectromagnetic radiation. In another embodiment, an emitting device 202may be comprised of one or more ultraviolet laser diodes for generatingthe electromagnetic radiation. An example of an ultraviolet laser diodeis Spectra-Physics laser diode LQC375-08E which radiates at about 375nm. In yet further embodiments, the electromagnetic radiation may befiltered, dispersed, or otherwise configured through the used ofexternal lenses, optical filters, or optical fibers to generate thedesired wavelengths. The illuminating device 104 is compatible andnon-detectable by infrared night vision equipment because the emittingdevices 202 generate electromagnetic radiation outside the sensitivityof night vision equipment. For example, a Night Vision Imaging System(NVIS) is sensitive between about 600 nm and 900 nm. Because theilluminating device 104 radiates well below the range of night visionequipment, the electromagnetic radiation does not cause blooming in thenight vision goggles of a pilot. Furthermore, the electromagneticradiation will not attract the unwanted attention of an observer on theground using night vision equipment. In yet further embodiments, theemitting devices 202 may be configured such that the electromagneticradiation is imperceptible to the human eye or night vision equipmentfrom a distance of at least one nautical mile away. The choice of thewavelength of the electromagnetic radiation can take advantage of theatmospheric scattering of short wavelengths, thus greatly attenuatingthe emission with observer distance.

FIG. 3 illustrates a block diagram of another embodiment of theilluminating device 104. In this embodiment, the illuminating device 104further comprises a configuring device 301 for configuring each one ofthe emitting devices 302 separately to adjust the intensity of theelectromagnetic radiation generated. The configuring device 301 may beimplemented with a variety of means such as power limiting devices,power control circuits, or computer controlled circuits and switches.The intensity of the illumination for the operation may be adjusted formore illumination or less illumination as necessary for optimallyviewing a display image of the operation through a camera vision system.

In yet another embodiment, the illuminating device 104 may furthercomprise a selecting device 303 for activating an “emission bank” 304.An emission bank 304 is a distinct group of emitting devices 302 thatare configured to be selected as a group for generating electromagneticradiation. Each individual emitting device 302 may be configured to oneor more emission banks 304. For example, FIG. 3 shows a first, second,and third emission bank 304 a, 304 b, and 304 c which are labeled in thedrawing as emission bank A, emission bank B, and emission bank Crespectively. If the first emission bank 304a is selected, then only thegroup of emitting devices 302 that are configured to emission bank 304 aare activated to generate electromagnetic radiation. The selectingdevice 303 may be implemented with a variety of means such as manuallyactivated electrical switches, automatic switches, or a computercontrolled switching circuit. Note that the configuration of emittingdevices 302 to an emission bank 304 is not limited to physicallyadjacent emitting devices 302. Furthermore, a particular emitting device302 may belong to more than one emission bank 304. For example, a subsetof the emitting devices 302 of second emission bank 304 b may also beconfigured to a separate emission bank 304. Or a subset of emittingdevices 302 from first emission bank 304 a and a subset of emittingdevices 302 from third emission bank 304 c could be configured to aseparate emission bank 304. In another embodiment, using the configuringdevice 301 and selecting device 303 allows the illuminating device 104to be spectrally reconfigurable. For example, first emission bank 304 amay be configured with emitting devices 302 that substantially radiateabout 420 nm, second emission bank 304 b may be configured with emittingdevices 302 that substantially radiate about 370 nm, and third emissionbank 304 c may be configured with emitting devices 302 that radiatethroughout a range from 370 to 420 nm with a particular distribution foreach wavelength. Because each emission bank 304 may be selectedindividually, the illuminating device 104 may be spectrally configurableas to a particular wavelength and its intensity. These embodiments ofconfiguring the intensity of the emitting devices 302 and selecting theemission banks 304 advantageously allows for adjusting the illuminatingdevice 104 for uniformly illuminating different types of receivingaircraft in an in-flight refueling operation, or controlling theillumination for the specific needs of other in-flight operations.

FIG. 4 illustrates a method 401 for transferring fuel from a supplyingaircraft to a receiving aircraft. In-flight fuel transfer requirescareful preparation and execution. Proper illumination is particularlyhelpful for refueling in a low light environment. However, as indicatedpreviously, it is desired that the illumination preferably does notattract unwanted attention. Accordingly, the method comprises anoperation 402 for generating electromagnetic radiation within thefar-violet and ultraviolet spectrum. Another operation 403 comprisesdirecting the electromagnetic radiation to the receiving aircraft forselectively and uniformly illuminating the receiving aircraft for therefueling operation. Using the illumination, an operation 404 isperformed to couple the supplying aircraft and receiving aircraft, andtransfer fuel from the supplying aircraft to the receiving aircraft. Theon-going fuel transfer and positions of the supplying and receivingaircraft are continuously monitored in another operation 405 until thefuel transfer is completed and the aircraft are decoupled. In anotherembodiment of the method, a further operation 406 comprises selecting anemission bank to activate a pre-established group of emitting devices.Still yet another embodiment comprises an operation 407 for configuringone or more emitting devices to adjust the power of the electromagneticradiation generated.

A device, method, and aircraft for illuminating an in-flight refuelingoperations using electromagnetic radiation within the far-violet andultraviolet spectrum have been disclosed. The scope of the invention isnot limited by the specific embodiments disclosed, and one skilled inthe art will understand there are other modifications and embodiments ofthe invention not described, but are in the scope of the claims thatfollow.

1.-9. (canceled)
 10. A method for performing an in-flight operationbetween a first aircraft and a second aircraft, the method comprising:configuring a first group from a plurality of emitting devices to afirst emission bank at the first aircraft; configuring a second groupfrom said plurality of emitting devices to a second emission bank at thefirst aircraft, wherein at least one of said plurality of emittingdevices is configured to both said first emission bank and said secondemission bank; selecting at least one of said first emission bank andsecond emission bank; generating electromagnetic radiation between about10 nanometers and about 420 nanometers from said selected emission bankat the first aircraft; and directing said electromagnetic radiation fromthe first aircraft to selectively illuminate the second aircraft whenthe second aircraft is in an in-flight refueling envelope.
 11. Themethod of claim 10, further comprising using said electromagneticradiation to illuminate the second aircraft to monitor and control theposition of the second aircraft in the in-flight refueling envelope. 12.The method of claim 10, further comprising using said electromagneticradiation to illuminate the second aircraft to transfer fuel from thefirst aircraft to the second aircraft.
 13. The method of claim 10,wherein said generating step comprises generating electromagneticradiation in a range between about 370 nanometers and about 420nanometers.
 14. (canceled)
 15. The method of claim 10, wherein saidgenerating step further comprises configuring an intensity of saidelectromagnetic radiation.
 16. A supplying aircraft configured totransfer fuel to a receiving aircraft, the supplying aircraftcomprising: a device adapted to generate electromagnetic radiationbetween about 10 nanometers and about 420 nanometers, said device havinga first group from a plurality of emitting devices configured to a firstemission bank, and a second group from said plurality of emittingdevices configured to a second emission bank, wherein at least one ofsaid plurality of emitting devices is configured to both said firstemission bank and said second emission bank, and said device having aselecting means for selecting at least one of first emission bank andsecond emission bank to illuminate the receiving aircraft when thereceiving aircraft is in an in-flight refueling envelope with thesupplying aircraft; a video camera aligned to view the receivingaircraft by utilizing said electromagnetic radiation; and a displaydevice for displaying the receiving aircraft.
 17. The supplying aircraftof claim 16 wherein said electromagnetic radiation is between about 370nanometers and about 420 nanometers.
 18. The supplying aircraft of claim16 wherein said illuminating device further comprises: a housingdisposed on the supplying aircraft; and at least one emitting devicedisposed in said housing and configured to generate electromagneticradiation between about 10 nanometers and about 420 nanometers; saidhousing being configured such that the electromagnetic radiation fromsaid at least one emitting device is capable of being directed to beincident on the receiving aircraft during the in-flight refuelingoperation.
 19. The supplying aircraft of claim 16 wherein said at leastone emitting device comprises a plurality of ultraviolet light emittingdiodes.
 20. The supplying aircraft of claim 16 wherein said at least oneemitting device comprises at least one ultraviolet laser diode.
 21. Thesupplying aircraft of claim 18 wherein said housing is configured suchthat said at least one emitting device disperses said electromagneticradiation in an arc between about 30 degrees and about 60 degrees. 22.(canceled)
 23. The supplying aircraft of claim 16, further comprising acontrol device to configure the intensity of said at least one emittingdevice.
 24. The method of claim 10 wherein at least one emitting deviceis comprised of a plurality of ultraviolet light emitting diodes. 25.The method of claim 10 wherein at least one emitting device is comprisedof at least one ultraviolet laser diode.